Currently, a digital video camera is available which has not only an IEEE1394 interface pursuant to the IEEE1394-1995 standard (see IEEE Std 1394-1995, IEEE Standard for a High Performance Serial Bus, Institute of Electrical and Electronics Engineers, Inc.) but also a USB interface pursuant to the USB 1.1 standard (see Universal Serial Bus Specification Revision 1.1, Sep. 23, 1998).
However, such a digital video camera suffers from a problem in that although an external apparatus connected to the USB interface is capable of accessing a memory card, an external apparatus connected to the IEEE1394 interface is not capable of accessing the memory card.
In the case where the digital video camera is constructed so that not only the external apparatus connected to the USB interface but also the external apparatus connected to the IEEE1394 interface are capable of accessing the memory card, there arises a problem in that it is required to prevent a situation where the two external apparatuses access the memory card at the same time. That is, there arises a problem in that it is required to exclusively control the external apparatuses that access the memory card. This problem is not limited to the memory card and similarly arises even for a removable medium other than the memory card.